Many work machines in the earth-moving, construction, and agricultural industries such as, for example, wheel loaders, motor graders, and agricultural tractors, may require high power applications. Generally, for such work machines, a continuously variable transmission with only one variator that includes a hydraulic pump and hydraulic motor is not sufficient for the high power requirements. As an example, one large variator, often times, is not sufficient for such high power applications. A second variator can be added to these transmissions to satisfy the high power requirements. In most cases, the second variator has the same large displacement as the first variator, which inherently requires more space on the work machine. Additionally, the output of the first variator is commonly connected in parallel to the output of the second variator so that the hydraulic pump and hydraulic motor of each variator rotate at the same speed. Traditionally, there is no reduction, however, between the two variators. In some situations, such as during low power applications, the large displacement of the second variator is more than is needed yet the outputs of the two variators remain tied to each other, which may lead to increased losses in the transmission.
U.S. Pat. No. 6,964,627 (the '627 patent) discloses a transmission that includes two planetary gear units and a single variator all connected together such that power can be transferred between an input and an output in a compound-split mode or an output-split mode. In the compound-split mode, the two planetary gear units are joined together at two connections to create two compound member branches and two single member branches. The variator operates a single hydraulic pump and a single hydraulic motor. The '627 patent does not disclose a transmission with two same or different sized variators having their outputs selectively combined.